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Supplemental Information <br /> The 871-DlU1 underground tank system was installed in 1982 and is located on <br /> the north side of Building 871. It supplies diesel fuel to a boiler in Building 871. <br /> The tank system consists of a 2,000-gallon single-walled carbon steel tank, and <br /> associated fill pipe, vent pipe, and fuel supply and return piping. Piping within <br /> and beneath concrete may be closed in place by draining, filling with slurry, and <br /> capping. Other piping will be removed. It is not known whether a concrete <br /> anchor pad is present beneath the tank. If a concrete anchor pad is present, it will <br /> be removed, if feasible. <br /> The system was registered with the State Water Resources Control Board in <br /> 1986 as 871-11D. It has been renamed 871-D1U1. Figure 1 (Appendix B) shows <br /> the location of Building 871 at Lawrence Livermore National Laboratory Site <br /> 300. Figure 2 shows location of tank 871-D1U1 with respect to Building 871. <br /> Figure 3 shows a plan view of the 871-D1U1 tank system along with the soil <br /> sample locations. <br /> UST 871-DlU1 has not leaked according to previous tank testing reports. The <br /> most recent test results, for the test performed in April 1994, are included as <br /> Appendix C. They show that the tank and associated underground piping are <br /> leak tight. <br /> Up to 10 cubic yards of suspected contaminated soil may be removed at the time <br /> of the tank removal. Soil samples will be collected below the tank and piping at <br /> the locations shown in Figure 3. If the results of analyses of the soil samples <br /> show that contamination is more than minor, or if there is an indication of <br /> contamination of groundwater, LLNL will perform additional investigation <br /> according to a workplan that will be developed in conjunction with San Joaquin <br /> County Public Health Services. Excavated soil will be sampled and disposed of <br /> properly. <br /> Water samples from the groundwater monitoring wells near 871-DlU1 (see <br /> Figure 4) are not currently analyzed for diesel fuel. If soil contamination is <br /> found, and if there is reason to suspect that the contaminants have migrated <br /> away from the closure site, groundwater samples from the monitoring wells will <br /> be analyzed for diesel fuel. However, groundwater contamination is not <br /> expected based on the results of leak tightness monitoring and the depth to <br /> groundwater of approximately 45 feet. <br /> A-1 <br />